Crystalline semiconductor film, method of manufacturing the same, and semiconductor device

ABSTRACT

A spin addition method for catalyst elements is simple and very important technique, because the minimum amount of a catalyst element necessary for crystallization can be easily added by controlling the catalyst element concentration within a catalyst element solution, but there is a problem in that uniformity in the amount of added catalyst element within a substrate is poor. The non-uniformity in the amount of added catalyst element within the substrate is thought to influence fluctuation in crystallinity of a crystalline semiconductor film that has undergone thermal crystallization, and exert a bad influence on the electrical characteristics of TFTs finally structured by the crystalline semiconductor film. The present invention solves this problem with the aforementioned conventional technique. If the spin rotational acceleration speed is set low during a period moving from a dripping of the catalyst element solution process to a high velocity spin drying process in a catalyst element spin addition step, then it becomes clear that the non-uniformity of the amount of added catalyst element within the substrate is improved. The above stated problems are therefore solved by applying a spin addition process with a low spin rotational acceleration to a method of manufacturing a crystalline semiconductor film.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a method of manufacturing a crystallinesemiconductor film containing silicon that is applied in an active layerof a thin film transistor (hereafter referred to as a TFT), and moreparticularly, to a spin addition method for a metallic element that hasan effect of promoting crystallization. Further, the present inventionrelates to a semiconductor device having the crystalline semiconductorfilm.

2. Description of the Related Art

Recently, techniques of forming semiconductor integrated circuits byforming TFTs on an insulating substrate, such as a glass substrate, havebeen progressed rapidly, and electro-optical devices, typically activematrix liquid crystal display devices, utilizing these techniques havebeen put into practical use. In particular, active matrix liquid crystaldisplay devices having integrated driver circuits are monolithic liquidcrystal display devices in which a pixel matrix circuit and a drivercircuit are formed on the same substrate, and the demand for theseactive matrix liquid crystal display devices has increased along withthe demand for making them higher definition. In addition, developmentsare also advancing toward the realization of system on panels havingbuilt-in logic circuits such as γ compensation circuits, memorycircuits, and clock generator circuits or the like.

However, it is necessary that driver circuits and logic circuits operateat high speed, and therefore the application of amorphous silicon filmsto the active layers, which form regions such as channel formingregions, source regions and drain regions in TFTs, is unsuitable. TFTshaving a polycrystalline silicon film as an active layer are coming intothe mainstream at present. The application of low-cost glass substratesas substrates for forming TFTs is demanded, and the development ofprocesses capable of being applied to glass substrates is flourishing.

For example, a technique is known in which a metallic element having acrystallization promotion effect, such as Ni (nickel) (hereafterreferred to simply as a catalyst element) is introduced into anamorphous silicon film, and then a crystalline silicon film is formed byheat treatment. It is clear that crystallization is possible by heattreatment if a temperature on the order of 550 to 600° C., less than theheat resistant temperature of the glass substrate, is used as the heattreatment temperature. It is necessary that the catalyst element beintroduced into the amorphous silicon film with this crystallizationtechnique. Methods such as plasma CVD, sputtering, evaporation, and spinaddition can be given as introduction methods.

A spin addition method, in which a solution containing a catalystelement (hereafter referred to as a catalyst element solution) is addedby spinning, is disclosed in JP 07-211636 A as a method of efficientlyintroducing a catalyst element into the vicinity of the surface of anamorphous silicon film. The spin addition method for the catalystelement solution as disclosed in the aforementioned unexamined patentapplication publication has the following characteristics:

(Characteristic 1) The amount of the catalyst element added to thesurface of the amorphous silicon film can easily be controlled bycontrolling the concentration of the catalyst element within thecatalyst element solution;

(Characteristic 2) The minimum amount of the catalyst element requiredin crystallization can therefore be added easily to the surface of theamorphous silicon film; and

(Characteristic 3) It is necessary to reduce the amount of the catalystelement within the crystallized crystalline silicon film as much aspossible for reliability and electrical stability of the semiconductordevice. The smallest amount of the catalyst element necessary forcrystallization can be easily added by regulating the catalyst elementconcentration of the catalyst element solution with the spin additionmethod, and therefore the introduction of an excess amount of thecatalyst element can be suppressed, which is advantageous forreliability and electrical stability of the semiconductor device.

The size of the glass substrates used in manufacturing of liquid crystaldisplay devices has been becoming larger in view of the goal ofapplications to large size screens and increasing productivity. It hasbeen projected that in the future, glass substrates that exceed 1 m on aside will be in use.

The above stated spin addition method for the catalyst element is one inwhich a liquid builds up on the substrate by dripping the catalystelement solution down onto the substrate surface, and the catalystelement solution that has been dripped down is then spun off by rotatingthe substrate at high velocity, thus adding a desired amount of thecatalyst element to the substrate surface. This spin addition method ischaracterized in that the amount of the catalyst element added to thesurface of the substrate can be easily controlled, and the like, andtherefore it is a very important technique that is currently undergoingconsideration for being put into practical use. However, there is aproblem in that the uniformity of the amount of added catalyst elementbecomes poor as the substrate size becomes larger. In particular, thenon-uniformity becomes a problem that cannot be ignored when thediagonal length of the square substrate is equal to or larger than 500mm.

The main reason that the uniformity becomes poor is thought to bebecause at the spin drying state after the catalyst element solution hasbeen applied to the substrate, the relative motion velocity with respectto air between the central portion of the substrate and regions in theperiphery of the substrate differ. Caused by this, the evaporation speedof solvent components of the catalyst element solution varies within thesurface of the substrate, and as a result, drying unevenness developbetween the central portion and the peripheral regions.

FIG. 3 is a diagram showing the relationship between the size of thesquare substrate and the motion velocity at the edge portions of thesubstrate, and the following can be considered as causes of thegeneration of drying unevenness. For example, if the catalyst elementsolution is added to a 250 mm square substrate by spin addition, themotion velocity of the central portion of the substrate with respect toair is 0 m/min when the rotational velocity is 500 rpm (500rotations/minute), while the edge portions of the substrate rotate at amotion velocity of approximately 400 m/min. Motion with respect to airthus becomes higher speed with increasing distance from the centralportion of the substrate, and therefore friction with the air becomessevere, and the solvent components of the catalyst element solutionevaporated very rapidly. Drying unevenness therefore develop due to thedifferences in evaporation speed of the solvent components between thecentral portion of the substrate and the edge portions of the substrate.

In addition, the drying unevenness caused by the different drying speedsof the solvent components tend to manifest at corner regions of thesquare substrate. It is thought that this is because air is pushed asidealong with rotational motion in the corner regions of the substrate, andtherefore the friction with the air becomes exceptionally severe there.These types of drying unevenness are large problems that influence theamount of deposited catalyst element, and that influence variousfluctuations, such as fluctuations in the final crystallization ratio,the size of crystal grains, and their alignment after crystallization.

SUMMARY OF THE INVENTION

The present invention has been made in view of solving the aboveproblems. Specifically, an object of the present invention is to resolveproblems with uniformity in the amount of added catalyst element withina substrate, caused by drying unevenness in a spin addition method.

As stated above, there is a fear of a problem of non-uniformity in theamount of added catalyst element within a substrate, caused by dryingunevenness during spin drying of a catalyst element solution in a spinaddition method for a metallic element (catalyst element) for promotingcrystallinity. In order to resolve the non-uniformity in the amount ofadded catalyst element within the substrate, it is necessary toeliminate the drying unevenness that occur during spin drying and whichare surmised to be the cause of the non-uniformity. The dryingunevenness during spin drying are thought to occur due to thedevelopment of a difference in evaporation speed for solvent componentsthat accompanies friction with the air when the substrate is rotating.

In order to solve the above-mentioned problems and, in the spin additionprocess for the catalyst element, to improve the uniformity within thesubstrate of the amount of the catalyst element deposited thereon. Thepresent invention takes a measure in which the rotational accelerationspeed up through a switch over to high velocity rotation is optimized inaccordance with the substrate size, thereby improving the uniformity ofthe amount of added catalyst element within the substrate.

Specifically, a method of manufacturing a crystalline semiconductor filmhas: a first step of depositing an amorphous semiconductor filmcontaining silicon on an insulating substrate; a second step of adding acatalyst element for promoting crystallization to the entire surface ofthe amorphous semiconductor film by a spin addition method; and a thirdstep of forming a crystalline semiconductor film containing silicon byheat treating the amorphous semiconductor film; in which the spinaddition method for the catalyst element is performed with a rotationalacceleration speed from 5 to 120 rpm/sec. Alternatively, the rotationalacceleration speed y in the spin addition process for the catalystelement is determined by the equation y<=Ax^(−B) (where x is thediagonal size of the substrate and A and B are constants).

Note that, in the case of adding the crystallization promoting catalystelement by the spin addition method, an addition method in accordancethe following spin addition method may also be employed. A maskinsulating film may be deposited onto an amorphous semiconductor film,and an opening region may be formed in a portion of the mask insulatingfilm, after which the crystallization promoting catalyst element may beadded to the mask insulating film by a spin addition method. The spinaddition method for the catalyst element is performed at a preconditionof a maximum fixed rotational velocity value of 800 to 1200 rpm.Addition of the solution containing the catalyst element is performed bydripping the solution during acceleration or during constant velocityrotation of the substrate, distributing the catalyst element over theentire surface.

Compared to a circular shape substrate, uniformity becomes poorer in thecase where the diagonal length of the square substrate is equal to orgreater than 500 mm with a conventional spin addition method. However,uniformity can be improved even if the diagonal of the substrate isequal to or greater than 500 mm by applying the aforementioned structureof the present invention. The amount of fluctuation in the amount ofadded catalyst element within the substrate is lowered in the case wherethe catalyst element is added by the spin addition method, and thereforethe uniformity in the crystallization ratio after crystallization, thegrain size, the grain arrangement, and the like can be enhanced, and auniform crystalline semiconductor film can be formed over the entiresurface of a large surface area substrate.

BRIEF DESCRIPTION OF THE DRAWINGS

In the accompanying drawings:

FIG. 1 is a graph showing the correlation between rotationalacceleration speed and amount of deposited Ni element (average value andfluctuation range);

FIG. 2 is a graph of the distribution of the amount of deposited Nielement deposited within a surface of a substrate;

FIG. 3 is a diagram of the relationship between substrate size andvelocity of movement at an edge portion of a substrate;

FIG. 4 is diagram showing a spin addition program of a method for spinaddition of a catalyst element, and a diagram of the relationshipbetween processing time and rotational velocity;

FIGS. 5A to 5F are substrate cross sectional diagrams showing a processof manufacturing a crystalline silicon film by a vertical growth method;

FIGS. 6A to 6E are substrate cross sectional diagrams showing a processof manufacturing a crystalline silicon film by a horizontal growthmethod;

FIGS. 7A and 7B are cross sectional diagrams showing a process ofmanufacturing an active matrix liquid crystal display device;

FIGS. 8A and 8B are cross sectional diagrams showing the process ofmanufacturing an active matrix liquid crystal display device;

FIGS. 9A and 9B are cross sectional diagrams showing the process ofmanufacturing an active matrix liquid crystal display device;

FIGS. 10A and 10B are cross sectional diagrams showing the process ofmanufacturing an active matrix liquid crystal display device;

FIGS. 11A and 11B are cross sectional diagrams showing the process ofmanufacturing an active matrix liquid crystal display device;

FIGS. 12A to 12F are device schematic diagrams showing examples ofsemiconductor devices having integrated liquid crystal display devices;

FIGS. 13A to 13D are device schematic diagrams showing examples ofsemiconductor devices having integrated liquid crystal display devices;

FIGS. 14A to 14C are device schematic diagrams showing examples ofsemiconductor devices having integrated liquid crystal display devices;

FIG. 15 is a graph showing the relationship between substrate size andNi concentration ratio between a center portion of the substrate and anedge portion of the substrate, taking rotational acceleration speed as aparameter; and

FIG. 16 is a graph showing the relationship between substrate size androtational acceleration speed, taking the Ni concentration ratio betweena center portion of the substrate and an edge portion of the substrateas a parameter.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiment Mode

[Improved Experiment of Spin Addition Method]

A spin addition method for a catalyst element is a method in which acatalyst element solution is dripped down onto a substrate surface,accumulated on the surface, and the dripped down catalyst elementsolution is then spread out by rotating the substrate at high velocity,thus a desired amount of the catalyst element being added to thesubstrate surface. A typical spin addition program for this spinaddition method is shown in FIG. 4. The horizontal axis in FIG. 4represents processing time (seconds), and the vertical axis representsrotational velocity of the substrate (units of rpm). The spin additionprocess proceeds in the following processing order: discharge ofcatalyst element solution during low velocity rotation, increase ofrotational velocity at constant acceleration, spin drying at fixedrotational velocity, and stopping rotation. In the spin drying at fixedrotational velocity process, the load on a spin motor during rotationbecomes larger along with increasing in size of the substrate, andtherefore the maximum permissible range for the rotational velocity islimited. For a case of a 320 mm×400 mm substrate size, the maximumpermissible range is on the order of 1200 rpm, and processing during thespin drying at fixed rotational velocity step is performed while fixedat the maximum permissible range of 1200 rpm. Therefore, a change in theprocessing is actually almost impossible.

Focusing on the rotational acceleration speed, a comparative evaluationof the uniformity in the amount of added catalyst element within thesubstrate was therefore performed while changing the rotationalacceleration speed during the increase of rotational velocity atconstant acceleration process. The main experimental conditions areshown in Table 1.

TABLE 1 Item Contents Substrate Corning 1737 substrate (thickness of 0.7mm × 320 mm Deposition of CVD Amorphous silicon film (50 nm)/underlayersilicon oxide film (150 nm) Catalyst element solution Nickel acetatesolution (10 ppm) Spin rotation program See FIG. 4 (spin accelerationspeed: 15, 30, 60, 120 rpm/second) Measurement on catalyst Totalreflection X-ray fluorescence analyzer within substrate element depositamount surface: Measurements at 9 points in diagonal directions

The substrate used in the experiment was a glass substrate, CorningCorp. 1737, having a thickness of 0.7 mm and a substrate size of 320mm×400 mm. In this experiment, a base film (in order to preventimpurities from diffusing from the glass substrate) made from a siliconoxide film having a film thickness of 150 nm is deposited on the glasssubstrate by plasma CVD, an amorphous silicon film having a filmthickness of 50 nm is deposited on the base film by plasma CVD, and a 10ppm aqueous nickel acetate solution is added by spinning as a catalystelement solution. Spin addition is performed in this experiment underfour rotational acceleration speed conditions: 15 rpm/sec, 30 rpm/sec,60 rpm/sec, and 120 rpm/sec. The amount of deposited nickel elements(hereinafter expressed by Ni elements) on the amorphous silicon film onthe substrate surface (strictly speaking, extremely thin silicon oxidefilm) was then measured by a total reflection X-ray fluorescenceanalyzer at 9 points in a diagonal direction within the surface of thesubstrate after the spin addition process was completed.

Note that if spin addition of the aqueous nickel acetate solution isperformed directly onto the amorphous silicon film, then the aqueousnickel acetate solution is repelled by the surface of the amorphoussilicon film because the wetting property of the amorphous silicon filmsurface are poor, and there is a problem in that uniform addition cannotbe performed. Strictly speaking, spin addition processing of the 10 ppmaqueous nickel acetate solution is therefore performed after forming anextremely thin silicon oxide film having a film thickness of 2 to 5 nmon the surface of the amorphous silicon film in order to improve thewetting property of the amorphous silicon film surface.

Experimental results are shown in FIG. 1. The horizontal axis of FIG. 1represents rotational acceleration speed (rpm/sec), and the verticalaxis represents the amount of deposited Ni elements (atoms/cm²). Fromthe results of FIG. 1, it can be seen that there is a tendency for theaverage value of the amount of deposited Ni elements (average of the 9points within the substrate surface) to decrease, and for thefluctuation range, which is the difference between the maximum andminimum values within the substrate surface, to increase along withincreasing rotational acceleration speed. In other words, it can be seenthat there is a tendency for the average value of the amount ofdeposited Ni elements to increase, and for the fluctuation in the amountof deposited Ni elements within the substrate surface to decrease, alongwith decreasing rotational acceleration speed. For example, the averagevalue of the amount of deposited Ni elements was 5.80×10¹² atoms/cm²,and the fluctuation range, which is the difference between the maximumand minimum values, was 1.28×10¹² atoms/cm² when the rotationalacceleration speed was 120 rpm/sec. For the case when the rotationalacceleration speed was 15 rpm/sec, however, the average value of theamount of deposited Ni elements was 7.64×10¹² atoms/cm², and thefluctuation range was 0.91×10¹² atoms/cm². It was confirmed that thefluctuation range become smaller with decreasing the rotationalacceleration speed.

The graph shown by FIG. 15 shows the results of investigating thedependence of the Ni concentration ratio between a central portion ofthe substrate and edge portions of the substrate on the substrate size(diagonal length). The rotational acceleration speed was changed from 15to 120 rpm/sec here, and the uniformity was improved as the rotationalacceleration speed was decreased. From the experimental results upthrough this point, it can be realized that the applicable range ofadded Ni is from 5×10¹² to 1×10¹³ atoms/cm² in the case where theamorphous silicon film is crystallized at a temperature equal to or lessthan 600° C. By keeping the Ni concentration within this range, uniformgrowth of crystal nuclei can be obtained, and crystallization can bereliably accomplished. It can be realized that if the concentrationbecomes higher than this concentration range, the Ni within acrystalline silicon film cannot be sufficiently removed by gettering,and the TFT characteristics will be worsened by the Ni remaining aftergettering. It is thus necessary to keep the permissible concentrationdifference within the substrate surface equal to or less than twice theminimum concentration. It can be confirmed that the domain size ofcrystalline silicon films manufactured under these conditions is in arange of 15 to 20 m within the substrate surface, and that there is auniform distribution. Note that the term domain size indicates the graindiameter observed by scanning electron microscopy after etching thesurface of the crystalline silicon film with Seco liquid. Furthermore,the equations shown in FIG. 15 are correlation equations between thefluctuation of the Ni concentration within the surface and the substratesize at accelerations of 1) 120 rpm/sec, 2)60 rpm/sec, 3) 30 rpm/sec,and 4) 15 rpm/sec.

The graph shown in FIG. 16 shows the relationship between substrate sizeand rotational acceleration speed. In the case where the permissibleconcentration difference (the Ni concentration ratio between the centralportion of the substrate and the edge portions) of the substrate is 2,the rotational acceleration speed y is expressed by the functiony=Ax^(−B) (where x is the diagonal dimension of the substrate (m), and yis the rotational acceleration speed (rpm/sec)), as incorporated in thegraph of FIG. 16. From the experimental values here, it can be giventhat A=457, and B=2. Rotational acceleration speeds capable of beingapplied may therefor be those equal to or less than y.

It is possible to reduce the fluctuation of the amount of deposited Nielement within the surface of the substrate by lowering the rotationalacceleration speed in the case where the substrate size is enlarged.However, there is a disadvantage in that the time required to reach thespin drying at fixed rotational velocity (1200 rpm) step becomes longerwith the reduced rotational acceleration speed, and the throughput ofthe overall spin addition process drops. If the relationship between therotational acceleration speed and the amount of processing time per onesubstrate is calculated with the amount of time for the spin drying atfixed rotational velocity (1200 rpm) step taken as 20 seconds, then atan acceleration of 60 rpm/sec, for example, it takes 40 seconds persubstrate, at 30 rpm/sec it takes 60 seconds, and at 15 rpm/sec, ittakes 100 seconds. It is therefore necessary to set a suitablerotational acceleration speed by weighing the effect of reducing thefluctuation within the substrate surface of the amount of deposited Nielements versus the drop in throughput. In the case where the substratesize is 320 mm×400 mm, it can be considered that a rotationalacceleration speed equal to or less than 30 rpm/sec, preferably between15 and 30 rpm/sec, is suitable.

Note that the rotational velocity in the spin drying at fixed rotationalvelocity step can also be considered to be further reduced than 1200 rpmwith an increase in the size of the substrate. For example, if thesubstrate size is 1 m square, a rotational velocity on the order of 800rpm is assumed, and a fixed 20 seconds for the spin drying at fixedrotational velocity (800 rpm) step is assumed for calculation, then theamount of processing time per one substrate is approximately 33 secondswhen the rotational acceleration speed is 60 rpm/sec, for example,approximately 47 seconds when the rotational acceleration speed is 30rpm/sec, and approximately 73 seconds when the rotational accelerationspeed is 15 rpm/sec. It is therefore also shown that a rotationalacceleration speed equal to or less than 30 rpm/sec is suitable for thecase of a 1 m square substrate size, and further, that a rotationalacceleration speed from 15 to 30 rpm/sec is suitable when consideringthe throughput of the spin addition process.

In addition, the distribution within the substrate surface of the amountof deposited Ni elements was also investigated experimentally, and theresults are shown in FIG. 2. Note that the experimental conditions arebasically the same as those of the experiment of FIG. 1, and a case ofusing 30 rpm/sec as the rotational acceleration speed was investigated.Further, the measurement points within the substrate surface consistedof 19 points in a diagonal direction from the substrate corner regions,19 points in the minor axis direction of the substrate (320 mmdirection), and 19 points in the major axis direction of the substrate(400 mm direction), that is, 57 measurement points in total.

From the results of FIG. 2, is can be seen that there is not a verylarge amount of fluctuation in the amount of deposited Ni elements inthe minor axis direction and the major axis direction of the substrate.However, the amount of deposited Ni elements increased specifically inthe substrate corner regions, and therefore it can be realized that thefluctuation in the amount of deposited Ni elements is particularlysevere in the diagonal direction. The cause of this is thought to bethat friction with the air is extraordinarily severe in the substratecorner regions during rotation of the substrate, and thereforeevaporation of solvent components in the Ni element aqueous solution dueto the friction becomes particularly large in the corner regions. Thefollowing can be thought when considering the cause in detail. Thesubstrate corner regions are positioned outside of an inscribed circularregion of the substrate, and therefore the substrate rotates withpushing aside air. It is considered that since the substrate cornerregions push aside air while rotationally moving, friction with the airbecomes extraordinarily harsh, and the evaporation of solvent componentsin the aqueous Ni element solution becomes especially large.

Note that the results of the first experiment, shown in FIG. 1, areexperimental results found by measuring at 9 points in the diagonaldirection of the substrate, and therefore these results reflect theinfluence of the extraordinary fluctuation in the substrate cornerregions. Considering the influence of the extraordinary fluctuation inthe substrate corner regions, the results of FIG. 1 therefore show thatlowering the rotational acceleration speed is effective in improving onthe non-uniformity of the amount of deposited Ni elements within thesubstrate. The results show that a rotational acceleration speed equalto or less than 30 rpm/sec is suitable, and further, that a rotationalacceleration speed between 15 and 30 rpm/sec is appropriate whenconsidering the throughput of the spin addition process.

In order to improve non-uniformity within a substrate of the amount ofdeposited catalyst element, from the above experiments it can be seenthat the non-uniformity in the amount of added catalytic element withina substrate is improved by reducing the rotational acceleration speed upthrough a switch over to high velocity rotation in a catalyst elementspin addition method. Note that, in the case where the substrate size isfrom 320 mm×400 mm to a 1 m square, it is considered that the rotationalvelocity of the spin drying at fixed rotational velocity step is on theorder of 800 to 1200 rpm. A rotational acceleration speed equal to orless than 30 rpm/sec is therefore suitable, and further, a rotationalacceleration speed from 15 to 30 rpm/sec is appropriate when consideringthe throughput of the spin addition process. Furthermore, if therotational acceleration speed is lowered, then the average value of theamount of added catalyst element increases, but it is considered thatthis can be coped with by regulating the concentration of the catalystelement solution.

Details of Catalyst Element Solution

The catalyst element solutions used by the spin addition method of thepresent invention are basically the same as the catalyst elementsolutions disclosed in JP 07-211636 A. The content in the aforementionedunexamined patent application publication relating to the catalystelement is as follows.

It is possible to use an aqueous solution or an organic solvents for thecatalyst element solution, and polar solvents such as pure water,alcohols, acids, and ammonium are preferable from the standpoint ofcatalyst element solubility. Further, it is also possible to applynon-polar organic solvents such as benzene, toluene, xylene, carbontetrachloride, chlorophyl, ether, trichloroethylene, andchlorofluorocarbons as solvents for containing the catalyst element.There are cases in which the catalyst element within solution isdissolved as a chemical compound, and cases in which the catalystelement is dissolved as a simple element.

In the case where Ni element is applied as the catalyst element, Nielements are normally introduced within solution as a Ni compound. Thefollowing can be given as typical Ni compounds: nickel bromide, nickelacetate, nickel oxalate, nickel carbide, nickel chloride, nickel iodide,nickel nitrate, nickel sulfate, nickel formate, nickel acetylacetate,2-ethylhexane nickel, 4-cyclohexyl butanoic acid, nickel oxide, andnickel hydroxide. Further, not only may nickel compounds be used, but amethod of dissolving simple Ni elements in acid may also be applied inthe case where the simple Ni elements are dissolved within a solution.Note that, although the preferable state of the Ni elements withinsolution is normally a state in which they are completely dissolved, anemulsion state in which Ni elements are dispersed uniformly may also beemployed.

It is also possible to apply metals other than Ni, such as Fe, Co, Ru,Rh, Pd, Os Ir, Pt, Cu, and Au, as the catalyst element. A method inwhich one catalyst element is dissolved within a solvent is generallyused as a method for applying the catalyst element, but a mixed solutionin which a plurality of types of catalyst elements are dissolved mayalso be used. Furthermore, similar to the Ni element case, thesecatalyst elements may be dissolved within solution in a chemicalcompound state, and may also be dissolved as simple catalyst elements inan acid without any particular problems.

Typical chemical compounds of the above catalyst elements are asfollows.

(Fe element): ferrous bromide, ferric bromide, ferric acetate, ferrouschloride, ferric fluoride, ferric nitrate, ferrous phosphate, ferricphosphate, and the like;

(Co element): cobalt bromide, cobalt acetate, cobalt chloride, cobaltfluoride, cobalt nitrate, and the like;

(Ru element): ruthenium chloride, and the like;

(Rh element): rhodium chloride, and the like;

(Pd element): palladium chloride, and the like;

(Os element): osmium chloride, and the like;

(Ir element): iridium trichloride, iridium tetrachloride, and the like;

(Pt element): platinic chloride, and the like;

(Cu element): cupric acetate, cupric chloride, cupric nitrate, and thelike; and

(Au element): gold trichloride, gold chloride, sodium tetrachloroaurate,and the like.

Method of Manufacturing Crystalline Semiconductor Film

Means of resolving the problems with the above conventional techniquesare discussed from the viewpoint of a method of manufacturing acrystalline semiconductor film containing silicon. Note that so-calledvertical growth methods and horizontal growth methods exist in themethod of manufacturing a crystalline semiconductor film containingsilicon, and that cases of each growth method are discussed here.

(1) Vertical Growth Method

A case of applying an improved spin addition method for a catalystelement in a vertical growth method for thermal crystallization isdiscussed. Thermal crystallization is performed after adding a catalystelement uniformly to the entire surface of an amorphous semiconductorfilm containing silicon. The vertical growth method is a crystal growthmethod in which thermal crystallization is performed after adding acatalyst element uniformly to the entire surface of an amorphoussemiconductor film containing silicon. Crystal growth proceeds in avertical direction from the surface of the amorphous semiconductor filmto which the catalyst element is added (a direction perpendicular to thesubstrate surface). This method is referred to as a vertical growthmethod in this specification.

(First step): An amorphous semiconductor film containing silicon isdeposited on an insulating substrate such as a glass substrate.

(Second step): A catalyst element having an effect of promotingcrystallization is added to the entire surface of the amorphoussemiconductor film by a spin addition method. Non-uniformity in theamount of added catalyst element within the substrate can be improvedhere by lowering the rotational acceleration speed up through a switchover to the spin drying at fixed rotational velocity step in the spinaddition method. Note that, in the case of using a large size substrate,up to a substrate having a size on the order of 1 m square, of which themaximum permissible range for the rotational velocity is on the order of800 to 1200 rpm, a rotational acceleration speed equal to or less than30 rpm/sec is suitable as the rotational acceleration speed.Furthermore, a rotational acceleration speed between 15 and 30 rpm/secis appropriate when considering the throughput of the spin additionprocess.(Third step): A crystalline semiconductor film containing silicon isformed by heat treating the amorphous semiconductor film (verticalgrowth method).

Further, in addition to the method of adding the catalyst element to theentire surface of the amorphous semiconductor film as above, a similareffect can also be obtained by performing the addition below theamorphous semiconductor film. For example, the catalyst element may alsobe added to the entire surface of the insulating substrate, or to theentire surface of a base film formed on the insulating substrate, by aspin addition method in accordance with the present invention.

(2) Horizontal Growth Method

A case of applying an improved spin addition method for a catalystelement in a horizontal growth method for thermal crystallization isdiscussed. Thermal crystallization is performed after selectively addinga catalyst element to a partial region of an amorphous semiconductorfilm containing silicon. The horizontal growth method is a crystalgrowth method in which thermal crystallization is performed, through anopening portion of a mask insulating film, after adding a catalystelement to a partial region of an amorphous semiconductor filmcontaining silicon. Crystallization proceeds in a horizontal direction(a direction parallel to the substrate surface) due to thermal diffusionin peripheral regions with the opening region as a starting point. Thismethod is referred to as a horizontal growth method in thisspecification.

(First step): An amorphous semiconductor film containing silicon isdeposited on an insulating substrate such as a glass substrate.

(Second step): A mask insulating film is deposited on the amorphoussemiconductor film, and an opening portion is formed in a partial regionof the mask insulating film.

(Third step): A catalyst element having an effect of promotingcrystallization is added on the mask insulating film by a spin additionmethod, thus introducing the catalyst element to the amorphoussemiconductor film through the opening region of the mask insulatingfilm. Non-uniformity in the amount of added catalyst element within thesubstrate can be improved here by lowering the rotational accelerationspeed while changing to the spin drying at fixed rotational velocitystep in the spin addition method. Note that, for cases of using a largesize substrate, up to a substrate having a size on the order of 1 msquare, of which the maximum permissible range for the rotationalvelocity is on the order of 800 to 1200 rpm, a rotational accelerationspeed equal to or less than 30 rpm/sec is suitable as the rotationalacceleration speed. Furthermore, a rotational acceleration speed between15 and 30 rpm/sec is appropriate when considering the throughput of thespin addition process.(Fourth step): A crystalline semiconductor film containing silicon isformed by heat treating the amorphous semiconductor film (horizontalgrowth method).

It is thus possible to improve the uniformity in the amount of addedcatalyst element within the substrate by applying the low rotationalacceleration speed spin addition method to the spin addition process forthe catalyst element in the method of manufacturing a crystallinesemiconductor film containing silicon using both the vertical growthmethod and the horizontal growth method. By improving the uniformity inthe amount of added catalyst element within the substrate, fluctuationwithin the substrate in the crystallinity of the crystallinesemiconductor film containing silicon obtained after thermalcrystallization can be reduced. This is considered to be effective instabilizing the electric characteristics of TFTs structured by thecrystalline semiconductor film.

Further, a term relating to amorphous semiconductor films containingsilicon is used in this specification. The term amorphous semiconductorfilm containing silicon refers to amorphous semiconductor films whichcontain silicon having semiconductor characteristics in accordance withcrystallization, and naturally encompasses amorphous silicon films, aswell as all amorphous semiconductor films containing silicon. Forexample, amorphous semiconductor films composed of a silicon andgermanium compound, denoted by the chemical formula Si_(1-x)Ge_(x)(where 0<x<1, and typically x=0.001 to 0.05) are also included.Furthermore, the term crystalline semiconductor film containing siliconis used for films obtained by crystallizing an amorphous semiconductorfilm containing silicon. The reason that polycrystalline is not usedhere, and crystalline is used is that, compared to a normalpolycrystalline semiconductor film, the crystalline semiconductor filmshere have unique properties in that their crystal grains are alignedsubstantially in the same direction, they have a high electric fieldeffect mobility, and the like.

Embodiment 1

A case of applying the spin addition method of the present invention toa catalyst element addition process in a method of manufacturing acrystalline silicon film by a vertical growth method is discussed indetail in embodiment 1 based on FIGS. 5A to 5F. Note that FIGS. 5A to 5Fare substrate cross sectional diagrams showing a process ofmanufacturing a crystalline silicon film by a longitudinal growthmethod.

First, an amorphous silicon film 102 is deposited at a film thickness of10 to 150 nm on a glass substrate 201 by reduced pressure CVD or plasmaCVD. In embodiment 1, a 100 nm thick film is deposited by plasma CVD forthe amorphous silicon film 102. An extremely thin natural oxide film 103(not shown) is formed on the surface of the amorphous silicon film 102during film deposition due to the influence of oxygen within the airthat is mixed into the processing atmosphere. (FIG. 5A)

Next, the substrate is cleaned for a predetermined amount of time bydilute hydrofluoric acid using a sheet-fed method cleaning process.Removal of the natural oxide film 103 formed on the surface of theamorphous silicon film 102 is performed by this process, and thesubstrate is then washed with water and dried (see FIG. 5B).

The surface of the amorphous silicon film 102 is then oxidized, forminga clean, extremely thin silicon oxide film 104 having a film thicknesson the order of 2 to 5 nm on the surface of the amorphous silicon film102. Although the extremely thin silicon oxide film 104 is formed by asheet-fed aqueous ozone process in embodiment 1, the film may also beformed by processing with aqueous hydrogen peroxide, and by generatingozone using ultraviolet (UV) irradiation within an oxygen atmosphere.Note that the film formation of the extremely thin silicon oxide film104 is a process which improves the wetting property with respect to theamorphous silicon film 102 when later adding an aqueous Ni elementsolution as a catalyst element solution, and in which Ni elements arethus allowed to adhere uniformly (see FIG. 5C).

The aqueous Ni element solution, which is a catalyst element solutionhaving an effect of promoting crystallization, is then added to theentire surface of the amorphous silicon film 102 (strictly speaking, theextremely thin silicon oxide film 104) by spin addition. A spin additionprocess is performed at this time, in which the substrate is placed on aspin chuck 105, and an aqueous Ni element solution 107 is built up onthe substrate from a supply nozzle 106 disposed above the substrate. TheNi compound nickel acetate is dissolved in pure water, the aqueous Nielement solution is regulated to have a concentration of 10 ppm Ni byweight, and spin addition is performed in a low velocity spin state of100 rpm in embodiment 1 (see FIG. 5D).

The rotational velocity of the substrate is then increased to 1200 rpmat a rotational acceleration speed of 30 rpm/sec, a low acceleration,after which spin drying is performed for 20 sec at 1200 rpm rotationalvelocity, making a Ni containing layer 108 adhere uniformly over theentire surface of the amorphous silicon film 102 (strictly speaking, theextremely thin silicon oxide film 104). (See FIG. 5E.)

Note that, in this embodiment, the rotational acceleration speed isreduced to 30 rpm/sec, half of the conventional rotational accelerationspeed (60 rpm/sec) when moving to high velocity rotation (1200 rpm)during spin addition of the Ni elements. Reducing the accelerationduring the spin addition process is effective in improvingnon-uniformity within the substrate of the amount of added Ni elements,but, on the other hand, this has a disadvantage in that the amount ofprocessing time for the Ni element addition process becomes longer. Itis therefore necessary to determine the acceleration used in the spinaddition process by considering the relative merits of the uniformitywithin the substrate in the amount of added Ni element, andproductivity. If the spin addition process is performed at anacceleration of 30 rpm/sec, then the amount of processing time for spinaddition per one substrate is approximately one minute, and there arealso no problems related to throughput. Further, the amount offluctuation in the amount of added Ni elements within the substrate canbe suppressed to the order of 60 to 70% of that found when processingunder conventional conditions (rotational acceleration speed: 60rpm/sec).

The amorphous silicon film 102 is then heat treated in a nitrogenatmosphere using a dedicated heat treatment furnace. The heat treatmentprocess has general characteristics in which crystallization isachieved, due to the action of the catalyst elements that promotecrystallization, by heat treatment performed at a temperature range of450 to 750° C. However, the processing time must be made longer if theprocessing temperature is low, thus lowering the production efficiency.Further, if processing is performed at a temperature equal to or higherthan 600° C., a problem with the heat resistance of the glass substrateapplied as the substrate will surface. A temperature range of 450 to600° C. is therefore proper for the heat treatment process temperaturefor cases in which a glass substrate is used. Furthermore, suitable heattreatment conditions for the actual heat treatment will also differ inaccordance with the method of depositing the amorphous silicon film 102.For example, it is sufficiently understood that heat treatment at 600°C. for 12 hours is appropriate if the amorphous silicon film 102 isdeposited by reduced pressure CVD, while heat treatment at 550° C. forfour hours is appropriate if the amorphous silicon film 102 is depositedby plasma CVD. The amorphous silicon film 102 is deposited by plasma CVDto have a film thickness of 100 nm in embodiment 1, and therefore acrystalline silicon film 109 is formed by performing heat treatment at550° C. for four hours. Note that the uniformity in the amount of addedNi element within the substrate can be improved, and therefore a uniformcrystal structure can also be obtained in the crystalline silicon film109 after thermal crystallization (see FIG. 5F).

It is thus possible to improve the uniformity of the amount of addedcatalyst element within the substrate by applying the catalyst elementspin addition method of the present invention to the method ofmanufacturing a crystalline silicon film by a vertical growth method.Further, in embodiment 1, the rotational acceleration speed in the spinaddition process for the Ni element catalyst elements is set to a lowacceleration of 30 rpm/sec, whereby the uniformity in the amount ofadded Ni element within the substrate and productivity can both beachieved.

Embodiment 2

The aqueous Ni element solution, the catalyst element solution having aneffect of promoting crystallization for amorphous silicon films, isapplied to the entire surface of the glass substrate 101 in FIG. 5A by aspin addition method in embodiment 1. Spin addition is performedsimilarly to that of embodiment 1. An amorphous silicon film is thendeposited, and a crystalline silicon film can be obtained by a verticalgrowth method by similarly performing heat treatment.

Further, a silicon nitride film, a silicon oxynitride film or the likemanufactured by plasma CVD or sputtering may also be formed to have athickness of 10 to 200 nm as a base film on the substrate 101.

Embodiment 3

A case of applying the spin addition method of the present invention toa catalyst element addition process in a method of manufacturing acrystalline silicon film by a horizontal growth method is discussed indetail in embodiment 3 based on FIGS. 6A to 6E. Note that FIGS. 6A to 6Eare substrate cross sectional diagrams showing a process ofmanufacturing a crystalline silicon film by a horizontal growth method.

First, an amorphous silicon film 202 is deposited at a film thickness of10 to 150 nm on a glass substrate 201 by reduced pressure CVD or plasmaCVD. In embodiment 3, a 100 nm thick film is deposited by plasma CVD forthe amorphous silicon film 202. An extremely thin natural oxide film(not shown) is formed on the surface of the amorphous silicon film 202during film deposition due to the influence of oxygen within the airthat is mixed into the processing atmosphere.

Next, a mask insulating film 203 made from a silicon oxide film having afilm thickness of 70 to 200 nm is deposited by plasma CVD. In embodiment3, the mask insulating film 203 is deposited by plasma CVD to have afilm thickness of 120 nm. An opening region 204 is then formed in apartial region of the mask insulating film 203 by a normalphotolithography process and etching process (generally, wet etching).The opening region 204 is a portion that becomes a selectiveintroduction region for a catalytic element (Ni elements are applied inembodiment 3), and the amorphous silicon film 202 is in an exposed statein the lower portion of the opening region 204. Note that although onlyone opening region is shown as a representation in FIG. 6A, in practice,a plurality of the opening regions 204 are formed at intervals ofseveral hundred micrometers (see FIG. 6A).

An extremely thin silicon oxide film 205 having a film thickness on theorder of 2 to 5 nm is then formed on the exposed region of the amorphoussilicon film 202 in the opening region 204 by oxidizing the substrate.The extremely thin silicon oxide film 205 is formed in embodiment 3 byaqueous ozone processing for a predetermined amount of time, but filmformation may also be performed by processing with aqueous hydrogenperoxide, and by generating ozone using ultraviolet (UV) lightirradiation in an oxygen atmosphere. Note that film formation of theextremely thin silicon oxide film 205 on the surface of the amorphoussemiconductor film 202 in the opening region 204 is performed in withthe goal of improving the wetting property of an aqueous Ni elementsolution with respect to the amorphous silicon film 202 in the openingregion 204 during later addition of the aqueous Ni element solution,which is a catalyst element solution, thus making Ni elements adhereuniformly (see FIG. 6B).

The aqueous Ni element catalyst element solution is then added on thesubstrate in order to selectively introduce Ni elements having an effectfor promoting crystallization in the partial region of the amorphoussilicon film 202, through the opening region 204. A spin additionprocess is performed at this time, in which the substrate is placed on aspin chuck 206, and an aqueous Ni element solution 208 is built up onthe substrate from a supply nozzle 207 disposed above the substrate. TheNi compound nickel acetate is dissolved in pure water, the aqueous Nielement solution is regulated to have a concentration of 10 ppm Ni byweight, and spin addition is performed in a low velocity spin state of100 rpm in embodiment 3 (see FIG. 6C).

The rotational velocity of the substrate is then increased to 1200 rpmat a rotational acceleration speed of 30 rpm/sec, a low acceleration,after which spin drying is performed for 20 sec at 1200 rpm rotationalvelocity, making a Ni containing layer 209 adhere uniformly over theentire surface of the substrate. Contributing to the actualcrystallization of the amorphous silicon film 202 is the Ni containinglayer 209 adhering to the surface of the amorphous silicon film 202(strictly speaking, the extremely thin silicon oxide film 205) withinthe opening region 204 (see FIG. 6D).

Note that, in embodiment 3, the rotational acceleration speed is reducedto 30 rpm/sec, half of the conventional rotational acceleration speed(60 rpm/sec) while moving to high velocity rotation (1200 rpm) duringspin addition of the Ni elements. Reducing the acceleration during thespin addition process is effective in improving non-uniformity withinthe substrate of the amount of added Ni elements, but, on the otherhand, this has a disadvantage in that the amount of processing time forthe Ni element addition process becomes longer. It is thereforenecessary to determine the acceleration used in the spin additionprocess by considering the relative merits of the uniformity within thesubstrate in the amount of added Ni element, and productivity. If thespin addition process is performed at an acceleration of 30 rpm/sec,then the amount of processing time for spin addition per one substrateis approximately one minute, and there are also no problems related tothroughput. Further, the amount of fluctuation in the amount of added Nielements within the substrate can be suppressed to on the order of 60 to70% of that found when processing under conventional conditions(rotational acceleration speed: 60 rpm/sec).

The substrate is then heat treated in a nitrogen atmosphere using adedicated heat treatment furnace. The heat treatment has generalcharacteristics in which crystallization of the amorphous silicon film202 is achieved, due to the action of the catalyst elements that promotecrystallization, by heat treatment performed at a temperature range of450 to 750° C. However, the processing time must be made longer if theprocessing temperature is low, thus lowering the production efficiency.Further, if processing is performed at a temperature equal to or higherthan 600° C., a problem with the heat resistance of the glass substrateapplied as the substrate will surface. A temperature range of 450 to600° C. is therefore proper for the heat treatment process temperaturefor cases in which a glass substrate is used. Heat treatment isperformed for 14 hours at a temperature of 570° C. within a nitrogenatmosphere in embodiment 3, thus crystallizing the amorphous siliconfilm 202 and forming a crystalline silicon film 210. The Ni elements areselectively introduced through the opening region 204 at this point, andtherefore the Ni elements diffuse into peripheral regions with theopening region 204 as an origin, crystallization of the amorphoussilicon film 202 proceeds in a horizontal direction (a directionparallel to the substrate surface) by the process of diffusion (see FIG.6E).

It is thus possible to improve the uniformity of the amount of addedcatalyst element within the substrate by applying the catalyst elementspin addition method of the present invention to the method ofmanufacturing a crystalline silicon film by a horizontal growth method.

Embodiment 4

The present embodiment is an example in which a catalyst element spinaddition method of the present invention is applied to a step ofmanufacturing a liquid crystal display device having the crystallinesilicon film by a horizontal growth method using catalyst element and isdescribed concretely with reference to FIGS. 7-11. Note that, the FIGS.7-11 shows the cross sectional view of manufacturing step for activematrix type liquid crystal display device.

First, a silicon oxynitride film 302 a with a thickness of 50 nm as thefirst layer and a silicon oxynitride film 302 b with a thickness of 100nm as the second layer that are different in composition ratio from eachother are deposited on a glass substrate 301 by the plasma CVD method toform a base film 302. Examples of the glass substrate 301 used hereininclude quartz glass, barium borosilicate glass, aluminoborosilicateglass, and the like. Next, an amorphous silicon film 303 a with athickness of 55 nm is deposited on the base film 302 (302 a and 302 b)by the plasma CVD method. In depositing the amorphous silicon film 303a, an ultrathin natural oxide film (not shown) is attached to thesurface of the amorphous silicon film 303 a due to the effect of oxygenin the air mixed into the treating atmosphere. Note that in the presentembodiment, the amorphous silicon film 303 a is deposited by the plasmaCVD method but may be formed by the low pressure CVD method (see FIG.7A).

During the deposition of the amorphous silicon film 303 a, there is apossibility that carbon, oxygen, and nitrogen present in the air may bemixed into the treating atmosphere. It has been known empirically thatcontamination by such impurity gases causes deterioration incharacteristics of TFTs eventually obtained. In view of this, It hasbeen recognized that the contamination by the impurity gases acts as afactor of crystallization inhibition. Hence, it is preferable tocompletely inhibit the impurity gases from being mixed into the treatingatmosphere. Specifically, it is preferable to set the impurity gasconcentration to be in the range of 5×10¹⁷ atoms/cm³ or less in both thecases of carbon and nitride and to be in the range of 1×10¹⁸ atoms/cm³or less in the case of oxygen (see FIG. 7A).

Next, the substrate is washed by a treatment with dilute hydrofluoricacid for a predetermined amount of time. For this treatment, the naturaloxide film (not shown) that is formed on the surface of an amorphoussilicon film 303 a is removed. Then the substrate is dried after aqueouswashing treatment. Afterward, oxidation treatment is conducted to theamorphous silicon film 303 a by aqueous ozone processing for apredetermined amount of time. For this oxidation treatment, a cleanextremely thin silicon film (not shown) is formed on the amorphoussilicon film 303 a and the substrate is dried. The extremely thinsilicon oxide film (not shown) is also formed by processing with aqueoushydrogen peroxide. Note that film formation of the extremely thinsilicon oxide film is performed in with the goal of improving thewetting property of an aqueous Ni element solution with respect to theamorphous silicon film 303 a during later addition of the aqueous Nielement solution, which is a catalyst element solution, thus making Nielements adhere uniformly (see FIG. 7 A).

The aqueous Ni element solution, the catalyst element solution having aneffect of promoting crystallization for amorphous silicon films isapplied to the entire surface of the amorphous silicon film 303 a(strictly, a extremely thin silicon oxide film which is not shown) by aspin addition process. In embodiment 4, nickel acetate as a Ni compoundis dissolved in pure water and then a Ni aqueous solution whoseconcentration has been controlled to be 10 ppm by weight conversion isapplied by a spin process. The rotational velocity of the substrate isthen increased to 1200 rpm at a rotational acceleration speed of 30rpm/sec, a low acceleration, after which spin drying is performed for 20sec at 1200 rpm rotational velocity, making a Ni containing layer (notshown) adhere uniformly over the entire surface of the amorphous siliconfilm 303 a (strictly, a extremely thin silicon oxide film which is notshown). (FIG. 7A)

Note that, in embodiment 4, the rotational acceleration speed is reducedto 30 rpm/sec, half of the conventional rotational acceleration speed(60 rpm/sec) while moving to high velocity rotation (1200 rpm) duringspin addition of the Ni elements. Reducing the acceleration during thespin addition process is effective in improving non-uniformity withinthe substrate of the amount of added Ni elements, but, on the otherhand, this has a disadvantage in that the amount of processing time forthe Ni element addition process becomes longer. It is thereforenecessary to determine the acceleration used in the spin additionprocess by considering the relative merits of the uniformity within thesubstrate in the amount of added Ni element, and productivity. If thespin addition process is performed at an acceleration of 30 rpm/sec,then the amount of processing time for spin addition per one substrateis approximately one minute, and there are also no problems related tothroughput. Further, the amount of fluctuation in the amount of added Nielements within the substrate can be suppressed to on the order of 60 to70% of that found when processing under conventional conditions(rotational acceleration speed: 60 rpm/sec).

Next, in order to control the amount of hydrogen contained in theamorphous silicon film 303 a to 5 atom % or less, the substrate isheat-treated in a nitrogen atmosphere at 450° C. for one hour, therebyimplementing dehydrogenation to remove the hydrogen contained in theamorphous silicon film 303 a (see FIG. 7B).

Next, a heat treatment is carried out in the electrothermal furnace at550° C. for four hours to crystallize the amorphous silicon film 303 aand thus a crystalline silicon film 303 b is formed. The crystallinesilicon film 303 b that is formed here hags the uniform grain structurein the substrate because which is applied uniformly over the substratein the step of spin addition of Ni element. Improving of uniformities ofgrain structure, the electrical characteristic of TFT made from thecrystalline silicon film 303 a is stabilized. (FIG. 7B).

Afterward, in order to improve the crystallinity of the crystallinesilicon film 303 b thus obtained, laser irradiation by a pulseoscillation type KrF excimer laser (with a wavelength of 248 nm) iscarried out with respect to the crystalline silicon film 303 b. Thisexcimer laser has not only an effect of improving the crystallinity ofthe crystalline silicon film 303 b but also an effect of improving theefficiency of gettering by a gettering source since the Ni element isbrought into a state where the Ni element can move very easily in thecrystalline silicon film 303 b (see FIG. 7B).

Next, pattern formation of the crystalline silicon film 303 b isconducted by the ordinary photolithography and dry etching to formsemiconductor films 304 to 308 to be channel, source, and drain regionsof TFTs. Note that, After the formation of semiconductor layer 304-308,for the Vth controle of TFT, channel doping that is n-type or p-typeimpurities (B: boron or P: Phosphorous) ion doping can be conducted.(see FIG. 8A).

Next, a gate insulating film 309 made of a silicon oxynitride film witha thickness of 100 nm is deposited by the plasma CVD method to cover thesemiconductor films 304 to 308. In depositing the gate insulating film309, the natural oxide film (not shown) attached to the surface of thesemiconductor film 304-308 is washed with dilute hydrofluoric acid.Afterward, a conductive film as a gate electrode material is depositedon the gate insulating film 309 by the sputtering method or the CVDmethod. As the gate electrode material used here, a heat resistantmaterial is preferable that can withstand the heat treatment temperature(about 550 to 650° C.) for gettering as a later step that also servesfor activating the impurity elements. Examples of the heat resistantmaterial include high melting metals such as Ta(tantalum),Mo(molybdenum), Ti(titanium), W(tungsten), Cr(chromium), and the like,metal silicide as a compound of a high melting metal and silicon,polycrystalline silicon having n-type or p-type conductivity, and thelike. Note that in the present embodiment, a gate electrode film 310formed from a W film with a thickness of 400 nm is deposited by thesputtering method (see FIG. 8B).

Above the substrate with the configuration described above are formedgate electrodes 317 to 320, an electrode 321 for storage capacitance,and an electrode 322 to function as a source wiring through theimplementation of photolithography and dry etching for the formation ofgate electrodes. After the dry etching, resist patterns 311 to 314 as amask for the dry etching remain on the gate electrodes 317 to 320.Similarly, resist pattern 315 remain on the electrode 321 for storagecapacitance and the electrode 322 to function as a source wiring,respectively. Note that the dry etching proceeds, the gate insulatingfilm 309 made of the silicon oxynitride film as a base is reduced inthickness to be deformed into a shape of a gate insulating film 323 (seeFIG. 9A).

Next, with the resist patterns 311 to 316 remaining, doping with a lowconcentration n-type impurity is carried out as a first ion dopingprocess using the ion doping apparatus with the gate electrodes 317 to320 and the electrode 321 for storage capacitance used as a mask. Theion doping process is carried out using a p element as an n-typeimpurity under the conditions including an accelerating voltage of 6 to100 kV and a dose of 3×10¹² to 3×10¹³ ions/cm². By this first ion dopingprocess, low concentration impurity regions (n⁻ regions) 329 to 333containing the n-type impurity are formed in the regions of thesemiconductor films 304 to 308 corresponding to the regions locatedoutside the respective gate electrodes 317 to 320 and the electrode 321for storage capacitance. At the same time, substantially intrinsicregions 324 to 327 to function as channels of the TFTs are formeddirectly under the gate electrodes 317 to 320. In the semiconductor film308 located directly under the electrode 321 for storage capacitance, anintrinsic region 328 to function as one of electrodes for capacitanceformation is formed since the region is not the TFT formation region butis a region where the storage capacitance 405 is to be formed (FIG. 9A).

Next, the substrate is washed with a special-purpose peeling liquid andthus the resist patterns 311 to 316 that have served as a mask for dryetching are removed. After the removal, in order to allow the n-channeltype TFTs 401 and 403 in a driving circuit 406 and the pixel TFT 404 ina pixel region 407 to have a lightly doped drain (LDD) structure, resistpatterns 334 to 336 for the formation of n⁺ regions to serve as a maskfor a second ion doping process are formed to cover the gate electrodes317, 319, and 320 that are present in the above-mentioned regions. (seeFIG. 9B).

Afterward, doping with a high-concentration n-type impurity is carriedout as the second ion doping process. The ion doping process is carriedout under the doping conditions including an accelerating voltage of 60to 100 kV and a dose of 1.7×10¹⁵ ions/cm². By this ion doping process,high-concentration impurity regions (REGIONS) 337, 339, and 340containing the n-type impurity are formed in the regions of thesemiconductor films 304, 306, and 307 corresponding to the regionslocated outside the resist patterns 334 to 336. With the formation ofthe high-concentration impurity regions (n⁺ regions) 337, 339, and 340,the low-concentration impurity regions (n⁻ regions) 329, 331, and 332that have already been formed are separated into the high-concentrationimpurity regions (n⁺ regions) 337, 339, and 340 and thelow-concentration impurity regions (n⁻ regions) 342 to 344 and thus thesource and drain regions to compose the LDD structure are formed. Atthis time, the region of the p-channel type TFT 402 of the drivingcircuit 406 and the region of the storage capacitance 405 in the pixelregion 407 that are regions other than the regions where the LDDstructures are formed are ion-doped with the gate electrode 318 and theelectrode 321 for storage capacitance used as a mask, respectively.Hence, high-concentration impurity regions (n⁺ regions) 338 containingthe n-type impurity are formed in the regions of the semiconductor film305 corresponding to the regions located outside the gate electrode 318,and high-concentration impurity regions (n⁺ regions) 341 containing then-type impurity are also formed in the regions of the semiconductor film308 corresponding to the regions located outside the electrode 321 forstorage capacitance (see FIG. 9B)

Next, by the ordinary photolithography, resist patterns 345 to 347 areformed with using as its opening regions the region of the semiconductorfilm 305 corresponding to the p-channel type TFT 402 and the region ofthe semiconductor film 308 corresponding to the storage capacitance 405.Afterward, with the resist patterns 345 to 347 used as a mask, dopingwith a high-concentration p-type impurity is carried out as a third iondoping process using the ion doping apparatus. By this ion dopingprocess, a boron element as a p-type impurity is ion-implanted into theregion of the semiconductor film 305 corresponding to the p-channel typeTFT 402 with the gate electrode 318 used as a mask. As a result,high-concentration impurity regions (p⁺ regions) 348 having p-typeconductivity are formed in the regions of the semiconductor film 305corresponding to the regions outside the gate electrode 318. Thehigh-concentration impurity regions (p⁺ regions) 348 have already beendoped with the phosphorous element as an n-type impurity but are dopedto contain a high concentration of boron element so that the dose of theboron element reaches 2.5×10¹⁵ atoms/cm². Thus, high-concentrationimpurity regions (p⁺ regions) 348 having p-type conductivity to functionas source and drain regions are formed. Similarly in the region wherethe storage capacitance 405 is formed, high-concentration impurityregions (p⁺ regions) 349 having p-type conductivity are also formed inthe regions of the semiconductor film 308 corresponding to the regionsoutside the electrode 321 for storage capacitance (see FIG. 10A).

Next, after the removal of the resist patterns 345 to 347, a firstinterlayer insulating film 350 made of a silicon oxynitride film with athickness of 150 nm is deposited by the plasma CVD method. Afterward,for the thermal activation of the impurity ions (the phosphorous andboron element) with which the semiconductor films 304 to 308 have beendoped, a heat treatment is carried out in an electrothermal furnace at600 C for 12 hours. This heat treatment is carried out for the thermalactivation of the impurity ions but also is intended to getter the Nielement present in the substantially intrinsic regions 324 to 327 tofunction as channel regions and the intrinsic region 328 to function asone of the electrodes for capacitance formation by the impurity ions.Note that the thermal activation may be carried out before thedeposition of the first interlayer insulating film 350. However, whenthe wiring materials for the gate electrodes or the like have low heatresistance, it is preferable to carry out the thermal activation afterthe deposition of the first interlayer insulating film 350. Afterward,in order to terminate unsaturated bonds present in the semiconductorfilms 304 to 308, a hydrogen treatment is carried out in a 3%hydrogen-containing nitrogen atmosphere at 410 C for one hour (see FIG.10B).

Next, a second interlayer insulating film 351 made from an acrylic resinfilm with a thickness of 1.6 ìm is formed on the first interlayerinsulating film 350. Afterward, contact holes are formed by the ordinaryphotolithography and dry etching so as to pass through the secondinterlayer insulating film 351, the first interlayer insulating film350, and the gate insulating film 323 as an underlayer film. At thistime, the contact holes are formed to be connected to the electrode 322to function as a source wiring and the high-concentration impurityregions 337, 339, 340, 348, and 349 (see FIG. 11A).

Next, conductive metal wirings 352 to 357 are formed to be electricallyconnected to the high-concentration impurity regions 337, 339, and 348of the driving circuit 406. Connection electrodes 358, 360, and 361 andgate wiring 359 in the pixel region 407 are formed with the sameconductive material. In the present embodiment, a laminated filmcomposed of a Ti film with a thickness of 50 nm and an Al—Ti alloy filmwith a thickness of 500 nm is applied as a constituent material for themetal wirings 352 to 357, the connection electrodes 358, 360, and 361,and the gate wiring 359. The connection electrode 358 is formed so as toelectrically connect the impurity region 340 with the electrode 322 tofunction as a source wiring. The connection electrode 360 is formed tobe electrically connected to the impurity region 340 of the pixel TFT404. The connection electrode 361 is formed to be electrically connectedto the impurity region 349 of the storage capacitance 405. In addition,the gate wiring 359 is formed to electrically connect a plurality ofgate electrodes 320 of the pixel TFT 404 to each other. Afterward, atransparent conductive film such as an indium tin oxide (ITO) film witha thickness of 80 to 120 nm is deposited and then a pixel electrode 362is formed by photolithography and etching. The pixel electrode 362 iselectrically connected to the impurity regions 340 as the source anddrain regions of the pixel TFT 404 through the connection electrode 360and is also electrically connected to the impurity region 359 of thestorage capacitance 405 through the connection electrode 361 (FIG. 11B).

As shown in above, in the manufacturing steps of active matrix typeliquid crystal device contained an n-channel type TFT having LDDstructure and a p-channel type TFT having single drain structure, spinadditional method with law rotational acceleration (rotationalacceleration speed 30 rpm/sec.) is applied to the spin additional stepsof catalyst element solution (aqueous element solution). Therefore, theamount of fluctuation in the amount of added Ni elements within thesubstrate can be suppressed to on the order of 60 to 70% of that foundwhen processing under conventional conditions (rotational accelerationspeed: 60 rpm/sec.) and homogeneous of the amount of added Ni element isimproved. By increasing the homogeneity of the crystalline structure inthe substrate, which have influence to the reduction of the amount offluctuation in the amount of crystallinity in the crystalline siliconfilm obtained after heat crystallization and also have good influence tothe stabilizing the electrical characteristic of TFT made from thecrystalline silicon film. Therefore, in the manufacturing method ofliquid crystal display device having crystalline silicon film usingcatalyst, the catalyst element spin additional method of this inventionis the important technique for the stabilizing the electricalcharacteristic of TFT.

Embodiment 5

The present invention relates to the method of manufacturing acrystalline semiconductor film containing silicon and which isapplicable to manufacturing various semiconductor devices. Therefore,the present invention can be applied to various semiconductor devicescomprising liquid display device as a display device. Examples of thesemiconductor device are shown in FIGS. 12 to 14. Following can be givenas such semiconductor device: video cameras; digital cameras; projectors(rear type or front type); head mounted displays (goggle type displays);game equipments; car navigation systems; personal computers; portableinformation terminals (mobile computers, portable telephones orelectronic books etc.) etc.

FIG. 12A is a personal computer which comprises: a main body 1001; animage input section 1002; a display portion 1003; and a key board 1004.The present invention can be applied to the display portion 1003 and theother circuit.

FIG. 12B is a video camera which comprises: a main body 1101; a displayportion 1102, a voice input section 1103; operation switches 1104; abattery 1105 and an image receiving section 1106. The present inventioncan be applied to the display portion 1102 and the other circuit.

FIG. 12C is a mobile computer which comprises: a main body 1201; acamera section 1202; an image receiving section 1203; operation switches1204 and a display portion 1205. The present invention can be applied tothe display portion 1205 and the other circuit.

FIG. 12D is a goggle type display which comprises: a main body 1301; adisplay portion 1302; and an arm section 1303. The present invention canbe applied to the display portion 1302 and the other circuit.

FIG. 12E is a player using a recording medium which records a program(hereinafter referred to as a recording medium) which comprises: a mainbody 1401; a display portion 1402; a speaker section 1403; a recordingmedium 1404; operation switches 1405. This device uses DVD (digitalversatile disc), CD, etc. for the recording medium, and can be used formusic appreciation, games and Internet. The present invention can beapplied to the display portion 1402 and the other circuit.

FIG. 12F is a mobile phone which comprises: a display panel 1501; anoperation panel 1502; a connecting portion 1503; a display portion 1504;a sound output portion 1505; an operation key 1506; a power switch 1507;a sound input portion 1508; and an antenna 1509. The display panel 1501and the operation panel 1502 are connected each other at the connectingportion 1503. The angle θ between the surface of the display panel 1501providing display portion 1504 and the surface of the operation panel1502 providing operation key 1506 can be changed arbitrarily in theconnecting portion 1503. The present invention can be applied to thedisplay portion 1504.

FIG. 13A is a front type projector which comprises: an optical lightsource system and a display portion 1601; and a screen 1602. The presentinvention can be applied to the display portion 1601 and the othercircuit.

FIG. 13B is a rear type projector which comprises: a main body 1701; anoptical light source system and a display portion 1702; a mirror 1703; amirror 1704; and a screen 1705. The present invention can be applied tothe display portion 1702 and the other circuit.

FIG. 13C is a diagram which shows an example of the structures of theoptical light source system and display portions 1601 and 1702 of FIGS.13A and 13B. Each of the optical light source system and displayportions 1601 and 1702 comprises: an optical light source system 1801;mirrors 1802 and 1804 to 1806; a dichroic mirror 1803; an optical system1807; a display portion 1808; a phase differentiating plate 1809; and aprojection optical system 1810. The projection optical system 1810comprises a plurality of optical lenses having a projection lens. Thisstructure is called as a three-plate type in which 3 display portions1808 are used. Further, an operator may appropriately dispose an opticallens, a film which has a function to polarize light, a film whichadjusts a phase difference and an IR film, etc in the optical path shownby an arrow in FIG. 13C.

FIG. 13D is a diagram showing an example of a structure of the opticallight source system 1801 in FIG. 13C. In the present embodiment, theoptical light source system 1801 comprises: a reflector 1811; a lightsource 1812; lens arrays 1813 and 1814; a polarizer conversion element1815; and a condensing lens 1816. Note that the optical light sourcesystem shown in FIG. 13D is merely an example and the structure is notlimited to this example. For instance, an operator may appropriatelydispose an optical lens, a film which has a function to polarize light,a film which adjusts a phase difference and an IR film, etc.

FIG. 14A is a diagram showing an example of a single plate type. Theoptical light source system and a display portion shown in FIG. 14Acomprises: an optical light source system 1901, a display portion 1902,a projection optical system 1903 and a phase difference plate 1904. Theprojection optical system 1903 comprises a plurality of optical lensesincluding a projection lens. The light source system and a displayportion shown in FIG. 14A can be applied to the optical light sourcesystems and display portions 1601 and 1702 shown in FIGS. 13A and 13B.An optical light source system shown in FIG. 13D may be used as theoptical light source system 1901. Note that a color filter is disposedin the display portion 1902 (not shown) and the displayed image iscolored.

An optical light source system and a display portion shown in FIG. 14Bis an application of FIG. 14A and the displayed image is colored byusing a rotating color filter circular plate 1905 of RGB in place ofdisposing a color filter. The light source system and a display portionshown in FIG. 14B can be applied to the optical light source systems anddisplay portions 1601 and 1702 shown in FIGS. 13A and 13B.

An optical light source system and a display portion shown in FIG. 14Cis called as a color-filter-less single plate system. This systemdisposes a micro lens array 1915 in the display portion 1916, and thedisplayed image is colored by using a dichroic mirror (green) 1912, adichroic mirror (red) 1913 and a dichroic mirror (blue) 1914. Theprojection optical system 1917 comprises a plurality of optical lensesincluding a projection lens. The light source system and a displayportion shown in FIG. 14C can be applied to the optical light sourcesystems and display portions 1601 and 1702 shown in FIGS. 13A and 13B.Further as an optical light source system 1911, an optical system usinga coupling lens and a collimator lens in addition to the light sourcemay be used.

As described above, the applicable range of the present invention isvery large, and it is possible to apply to semiconductor devicecomprising active matrix type liquid display device of various fields.

The present invention relates to a method of manufacturing a crystallinesemiconductor film containing silicon. In particular, the presentinvention relates to a method of spin addition for a catalyst element,the method characterized by low rotational acceleration speed, and themain effects are listed below.

(Effect 1) It is possible to improve the uniformity of the amount ofadded catalyst element within a substrate by reducing the rotationalacceleration speed until moving to high velocity rotation for spindrying in the spin addition process for the catalyst element.(Effect 2) It is possible to improve the uniformity of the amount ofadded catalyst element within the substrate by reducing the rotationalacceleration speed to a value equal to or less than 30 rpm/sec untilmoving to high velocity rotation for spin drying in the spin additionprocess for the catalyst element. Further, it is possible to increasethe uniformity of the amount of added catalyst element within thesubstrate, and to maintain throughput of the spin addition process, bysetting the rotational acceleration speed to between 15 and 30 rpm/sec.(Effect 3) A reduction in fluctuation in crystallinity within thesubstrate in a crystalline silicon film containing silicon obtainedafter thermal crystallization can be obtained by improving theuniformity of the amount of added catalyst element within the substrate,and this is therefore effective in stabilizing the electricalcharacteristics of TFTs structured by the crystalline semiconductorfilm.

1. A method of manufacturing a crystalline semiconductor film containingsilicon, said method comprising: a first step of depositing an amorphoussemiconductor film containing silicon over an insulating substrate; asecond step of adding a metallic element for promoting crystallizationto an entire surface of the amorphous semiconductor film by a spinaddition method; and a third step of forming the crystallinesemiconductor film by heat treating the amorphous semiconductor film;wherein a rotational acceleration speed y in the spin addition methodsatisfies y≦Ax^(−B) (where x is a diagonal dimension of the insulatingsubstrate, and A and B are constant).
 2. A method of manufacturing acrystalline semiconductor film according to claim 1, wherein theinsulating substrate has a square shape.
 3. A method of manufacturing acrystalline semiconductor film according to claim 1, wherein a length ofa diagonal of the insulating substrate is equal to or larger than 500mm.
 4. A method of manufacturing a crystalline semiconductor filmaccording to claim 1, wherein the maximum value of a rotational velocityin the spin addition method is from 800 to 1200 rpm.
 5. A method ofmanufacturing a crystalline semiconductor film according to claim 1,wherein the second step is one in which a solution containing themetallic element is dripped onto the entire surface of the amorphoussemiconductor film over the insulating substrate while the substrate isrotating.
 6. A method of manufacturing a crystalline semiconductor filmaccording to claim 1, wherein the metallic element is added by spinningusing a solution containing one element or a plurality of elements, saidelement or said plurality of elements selected from the group consistingof Fe, Co, Ni, Ru, Rh, Pd, Os, Ir, Pt, Cu, and Au.
 7. A method ofmanufacturing a crystalline semiconductor film containing silicon, saidmethod comprising: providing an amorphous semiconductor film containingsilicon over an insulating substrate; providing a solution including ametallic element for promoting crystallization on a surface of theamorphous semiconductor film while rotating the insulating surface; andheating the amorphous semiconductor film to form the crystallinesemiconductor film, wherein a rotational acceleration speed y inrotating the insulating substrate satisfies y≦Ax^(−B) (where x is adiagonal dimension of the insulating substrate, and A and B areconstant).
 8. A method of manufacturing a crystalline semiconductor filmaccording to claim 7, wherein the insulating substrate has a squareshape.
 9. A method of manufacturing a crystalline semiconductor filmaccording to claim 7, wherein a length of a diagonal of the insulatingsubstrate is equal to or larger than 500 mm.
 10. A method ofmanufacturing a crystalline semiconductor film according to claim 7,wherein the maximum value of a rotational velocity in rotating theinsulating substrate is from 800 to 1200 rpm.
 11. A method ofmanufacturing a crystalline semiconductor film according to claim 7,wherein the solution containing the metallic element is dripped onto thesurface of the amorphous semiconductor film over the insulatingsubstrate while the surface is rotating.
 12. A method of manufacturing acrystalline semiconductor film according to claim 7, wherein themetallic element is a solution containing one element or a plurality ofelements, said element or said plurality of elements selected from thegroup consisting of Fe, Co, Ni, Ru, Rh, Pd, Os, Ir, Pt, Cu, and Au. 13.A method of manufacturing a crystalline semiconductor film comprisingsilicon, said method comprising: a first step of adding a metallicelement for promoting crystallization of an amorphous semiconductor filmto an insulating surface by a spin addition method; a second step ofdepositing an amorphous semiconductor film containing silicon on theinsulating surface; and a third step of forming the crystallinesemiconductor film by heat treating the amorphous semiconductor film,wherein a rotational acceleration speed y in the spin addition methodsatisfies y≦Ax^(−B) (where x is a diagonal dimension of a substratehaving the insulating surface, and A and B are constant).
 14. A methodof manufacturing a crystalline semiconductor film according to claim 13,wherein the substrate has a square shape.
 15. A method of manufacturinga crystalline semiconductor film according to claim 13, wherein a lengthof a diagonal of the substrate is equal to or larger than 500 mm.
 16. Amethod of manufacturing a crystalline semiconductor film according toclaim 13, wherein the maximum value of a rotational velocity in the spinaddition method is from 800 to 1200 rpm.
 17. A method of manufacturing acrystalline semiconductor film according to claim 13, wherein in thethird step a solution containing the metallic element is dripped ontothe insulating surface.
 18. A method of manufacturing a crystallinesemiconductor film according to claim 13, wherein the metallic elementis added by spinning using a solution containing one element, or aplurality of elements, selected from the group consisting of Fe, Co, Ni,Ru, Rh, Pd, Os, Ir, Pt, Cu, and Au.
 19. A method of manufacturing acrystalline semiconductor film according to claim 13, wherein themetallic element is added to the insulating surface of a base film bythe spin addition method after forming the base film on the substrate.20. A method of manufacturing a crystalline semiconductor filmcomprising silicon, said method comprising: a first step of depositingan amorphous semiconductor film containing silicon on an insulatingsurface; a second step of depositing a mask insulating film on theamorphous semiconductor film, and forming an opening region in a portionof the mask insulating film; a third step of adding a metallic elementfor promoting crystallization to the mask insulating film by a spinaddition method; and a fourth step of forming a crystallinesemiconductor film by heat treating the amorphous semiconductor film,wherein a rotational acceleration speed y in the spin addition methodsatisfies y≦Ax^(−B) (where x is a diagonal dimension of a substratehaving the insulating surface, and A and B are constant).
 21. A methodof manufacturing a crystalline semiconductor film according to claim 20,wherein the substrate has a square shape.
 22. A method of manufacturinga crystalline semiconductor film according to claim 20, wherein a lengthof a diagonal of the substrate is equal to or larger than 500 mm.
 23. Amethod of manufacturing a crystalline semiconductor film according toclaim 20, wherein the maximum value of a rotational velocity in the spinaddition method is from 800 to 1200 rpm.
 24. A method of manufacturing acrystalline semiconductor film according to claim 20, wherein in thethird step a solution containing the element is dripped onto the maskinsulating film.
 25. A method of manufacturing a crystallinesemiconductor film according to claim 20, wherein the metallic elementis added by spinning using a solution containing one element, or aplurality of elements, selected from the group consisting of Fe, Co, Ni,Ru, Rh, Pd, Os, Ir, Pt, Cu, and Au.
 26. A method of manufacturing acrystalline semiconductor film according to claim 20, wherein theamorphous semiconductor film is deposited on the insulating surface of abase film after forming the base film on the substrate.
 27. A method ofmanufacturing a crystalline semiconductor film containing silicon, saidmethod comprising: providing a metallic element for promotingcrystallization on an insulating surface that a substrate has whilerotating the substrate; providing an amorphous semiconductor filmcontaining silicon on the insulating surface; and heating the amorphoussemiconductor film to form the crystalline semiconductor film, wherein arotational acceleration speed y in rotating the substrate satisfiesy≦Ax^(−B) (where x is a diagonal dimension of the substrate, and A and Bare constant).
 28. A method of manufacturing a crystalline semiconductorfilm according to claim 27, wherein the substrate has a square shape.29. A method of manufacturing a crystalline semiconductor film accordingto claim 27, wherein a length of a diagonal of the substrate is equal toor larger than 500 mm.
 30. A method of manufacturing a crystallinesemiconductor film according to claim 28, wherein the maximum value of arotational velocity in rotating the substrate is from 800 to 1200 rpm.31. A method of manufacturing a crystalline semiconductor film accordingto claim 27, wherein a solution including the metallic element isdripped onto the insulating surface.
 32. A method of manufacturing acrystalline semiconductor film according to claim 27, wherein themetallic element is at least one element selected from the groupconsisting of Fe, Co, Ni, Ru, Rh, Pd, Os, Ir, Pt, Cu, and Au.
 33. Amethod of manufacturing a crystalline semiconductor film according toclaim 27, further comprising: forming a base film having the insulatingsurface on the substrate before providing the metallic element on theinsulating surface.
 34. A method of manufacturing a crystallinesemiconductor film containing silicon, said method comprising: providingan amorphous semiconductor film on an insulating surface that asubstrate has; providing an insulating film as a mask on the amorphoussemiconductor film; forming an opening in a portion of the insulatingfilm; providing a metallic element for promoting crystallization on theopening while rotating the substrate; and heating the amorphoussemiconductor film to form the crystalline semiconductor film, wherein arotational acceleration speed y in rotating the substrate satisfiesy≦Ax^(−B) (where x is a diagonal dimension of the substrate, and A and Bare constant).
 35. A method of manufacturing a crystalline semiconductorfilm according to claim 34, wherein the substrate has a square shape.36. A method of manufacturing a crystalline semiconductor film accordingto claim 34, wherein a length of a diagonal of the substrate is equal toor larger than 500 mm.
 37. A method of manufacturing a crystallinesemiconductor film according to claim 34, wherein the maximum value of arotational velocity in rotating the substrate is from 800 to 1200 rpm.38. A method of manufacturing a crystalline semiconductor film accordingto claim 34, wherein a part of a solution including the metallic elementis dripped onto the opening.
 39. A method of manufacturing a crystallinesemiconductor film according to claim 34, wherein the metallic elementis at least one element selected from the group consisting of Fe, Co,Ni, Ru, Rh, Pd, Os, Ir, Pt, Cu, and Au.
 40. A method of manufacturing acrystalline semiconductor film according to claim 34, furthercomprising: forming a base film having the insulating surface on thesubstrate before providing the amorphous semiconductor film on theinsulating surface.